A Super Bubble Candidate in the Galactic Center and a Local Enhancement G359.77$-$0.09

Abstract

Abstract A 20$^\prime$$\times$ 16$^\prime;$ elliptical ring-like structure has been found near the Galactic center in the narrow energy band corresponding to the K$\alpha$ line from He-like sulfur. In the ring, two diffuse sources are found, a supernova remnant candidate, G359.79$-$0.26, and an unidentified source, G359.77$-$0.09. The X-ray spectrum of G359.77$-$0.09 is similar to that of G359.79$-$0.26, which can be explained by an absorbed thin thermal plasma model with temperatures of 0.7 and 1.0 keV. The absorption column densities of these two sources are large ($N_{\rm H}$$=$ 6.9 $\times$ 10$^{22}$ and 4.5 $\times$ 10$^{22}$cm$^{-2}$) and are consistent with that of the Galactic center distance. The X-ray spectrum extracted from the ring-like structure is also represented by an absorbed thin thermal plasma model ($kT_{\rm e}$$\sim$ 0.9 keV). The thermal energy of the plasma filling the ring-like structure is estimated to be 1.0 $\times$ 10$^{51}$erg. We therefore propose that the two sources comprise a single ring-like object, which is possibly a super bubble with a size of 49 pc $\times$40 pc in the Galactic center region.